PROCESS FOR PRODUCING TAXANE DITERPENE AND METHOD OF HARVESTING CULTRED CELL CAPABLE OF PRODUCING TAXANE DITERPENE IN HIGH YIELD

Abstract: A process for producing a taxane diterpene which comprises culturing the tissue or cell of a plant that produces a taxane diterpene in the presence of at least one member selected from the group consisting of jasmonic acids, heavy metal compounds, heavy metal complex ions, heavy metal ions, amines and ethylene-resisting agent; another process for producing a taxane diterpene which comprises culturing the tissue or cell by controlling the condition from the outset such that the oxygen concentration in the gas phase within the culture vessel is lower than the atmospheric oxygen concentration or that the dissolved oxygen concentration in the flowable medium in contact with the tissue or cell is lower than the saturation dissolved oxygen concentration at that temperature; still another process for producing a taxane diterpene which comprises culturing the tissue or cell in a culture tank by flowing into the tank an oxygenic gas containing 0.03-10 % of carbon dioxide; and a method of harvesting a cultured cell capable of producinga taxane diterpene in a high yield which comprises distributing the cells among a number of layers on the basis of a difference in specific gravity, culturing the cells contained in at least one of the layers, and selecting the target cell from among the cells thus cultured. The invention permits industrial production of taxane diterpenes such as taxol useful as a cancer remedy.

Description: Technical Field This invention relates to a method of producing a taxane-type diterpene including taxol which is useful as a therapeutic agent for ovarian cancer, mammary cancer, lung cancer and the like, and a method of obtaining cultured cells which produce the taxane-type diterpene at a high rate. Background Art Taxol, which is useful as a therapeutic agent for ovarian cancer, mammary cancer, lung cancer and the like, is a taxane-type diterpene identified after being isolated from Taxus brevifolia NUTT, which is a plant belonging to genus Taxus, family Taxaceae and has a complex ester group which is related to its activity. Taxol can be found in all the parts of the plant body of Taxus brevifolia NUTT, but the bark has been reported to exceed all others in its content of the taxol. At present, taxol is collected from a natural or a cultivated plant body, however, the plant belonging to genus Taxus grows slowly, and it takes more than 10 years to grow to a height of 20 cm above the ground, besides the tree dies after its bark is taken off, thus it has been difficult to easily obtain a large amount of taxol. It would be advantageous if a taxane-type diterpene such as taxol and baccatin III which is a precursor of taxol, can be produced by the use of tissue culture, since a large amount of taxol can be easily obtained without cutting down the trees. As a conventional method of producing taxol by utilizing cultured plant cells, a US patent was issued on a production method utilizing cultured cells of Taxus brevifolia NUTT (USP No. 5,019,504), however, the yield of taxol production described therein is 1 - 3 mg/l, and that is insufficient for the industrial production. Besides, the production of taxol by the cell culture is unstable and even when a primary cell of high productivity can be obtained by selection, it is difficult to keep its content by subculturing [E.R.M.Wickremesine et al., World Congress on Cell and Tissue Culture (1992)]. On the other hand, as a prior art in the taxol production, a semisynthetic method from baccatin III, which is a precursor in biosynthesis of taxol, is disclosed in the specification of USP No. 5,015,744 issued to Holton et al. By the use of the plant tissue culture, a raw material for the semisynthetic process such as baccatin III can be produced, thus the plant tissue culture can be also utilized for taxol production by the above-mentioned semisynthetic process. Disclosure of Invention The first object of the present invention is to provide a simple method of producing a taxane-type diterpene by plant tissue culture. The second object of the present invention is to provide a method of obtaining cultured cells which produce a taxane-type diterpene at a high rate. The invention of the present application is a method of producing a taxane-type diterpene wherein a tissue or a cell of a plant which produces a taxane-type diterpene is cultured in the presence of at least one substance selected from the group consisting of jasmonic acids, [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- , then the taxane-type diterpene is recovered from the resulting cultures. A further method of the present application is a method of producing a taxane-type diterpene wherein a tissue or a cell of a plant which produces a taxane-type diterpene is cultured by controlling the oxygen concentration in a gas phase in a culture vessel to less than the oxygen concentration in the atmosphere, from the initial stage of the culture, or by controlling the dissolved oxygen concentration in a fluid medium which is in contact with the tissue or the cell to less than the saturated dissolved oxygen concentration at that temperature, from the initial stage of the culture, then the taxane-type diterpene is recovered from the resulting cultures. A further method of the present application is a method of obtaining cultured cells which produce a taxane-type diterpene at a high rate, wherein cells of a plant which produces a taxane-type diterpene are fractionated into a plurality of layers according to the difference in their specific gravities, and cells contained in at least one layer are cultured, then such cultured cells that produce the taxane-type diterpene at a high rate are selected from amcnc those cultured cells. The present invention will be described in further detail. The taxane-type diterpene, which is an object for the present invention, is not particularly limited to any diterpene as far as it has a taxane skeleton, and the illustrative examples include taxol, 7-epitaxol, baccatin III, 7-epibaccatin III, cephalomannine, 7-epicephalomannine, 10-deacetylbaccatin III, 10-deacetylcephalomannine, 10-deacetyltaxol, taxagifine, an analogue thereof, taxane 1a, an analogue thereof, xylosyl cephalomannine, xylosyl taxol and the like. Examples of the plant to be used in the present invention which produces the taxane-type diterpene are those belonging to genus Taxus, such as Taxus baccata LINN, Taxus cuspidata SIEB. et ZUCC, Taxus cuspidata SIEB. et ZUCC var. nana REHDER, Taxus brevifolia NUTT, Taxus canadensis MARSH, Taxus chinensis, and Taxus media. According to the invention of the present application, culture of the above-mentioned plant can be carried out by the previously known method except that the tissue or the cell of the plant which produces the taxane-type diterpene is cultured in the presence of at least one substance selected from the group consisting of jasmonic acids, [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . Examples of jasmonic acids include a compound represented by the general formula (I): [wherein, R 1a , R 1b , R 1c , R 1d , R 1e and R 1f respectively represent hydrogen atom, hydroxyl group, alkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms; R 2 , R 3 , R 4 , R 5 and R 6a respectively represent hydrogen atom or alkyl group having 1 to 6' carbon atoms; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain one or more double bonds; R 6b represents hydroxyl group or -O- carbohydrate residue; R 7 represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8 (wherein R 8 represents hydrogen atom, acyl group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms or amino acid residue), OR 9 (wherein R 9 is alkyl group having 1 to 6 carbon atoms or carbohydrate residue), or alkyl group having 1 to 6 carbon atoms; n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms], a compound represented by the general formula (II): [wherein, R 1a , R 1b , R 1c , R 1d , R 1e and R 1f respectively represent hydrogen atom, hydroxyl group, alkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms; R 2 , R 3 , R 4 , R 5 and R 6 respectively represent hydrogen atom or alkyl group having 1 to 6 carbon atoms; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain one or more double bonds; R 7 represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8 (wherein R 8 represents hydrogen atom, acyl group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms or amino acid residue), OR 9 (wherein R 9 is alkyl group having 1 to 6 carbon atoms or carbohydrate residue), or alkyl group having 1 to 6 carbon atoms; n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms], and a compound represented by the general formula (III): [wherein, R 1a , R 1b , R 1c , R 1d , R 1e and R 1f respectively represent hydrogen atom, hydroxyl group, alkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms; R 2 , R 3 , R 4 , R 5 and R 6 respectively represent hydrogen atom or alkyl group having 1 to 6 carbon atoms; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain one or more double bonds; R 7 represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8 (wherein R 8 represents hydrogen atom, acyl group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms or amino acid residue), OR 9 (wherein R 9 is alkyl group having 1 to 6 carbon atoms or carbohydrate residue), or alkyl group having 1 to 6 carbon atoms; n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. Preferable examples of jasmonic acids represented by the above-mentioned general formula (I) include a compound represented by the general formula (I'): [wherein, R 1' represents hydrogen atom or hydroxyl group; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 ; R 6b represents hydroxyl group or -O- carbohydrate residue; R 7' represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8' (wherein R 8' represents hydrogen atom, acyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms or amino acid residue) or OR 9' (wherein R 9' represents alkyl group having 1 to 4 carbon atoms or carbohydrate residue); n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms], and preferable examples of jasmonic acids represented by the above-mentioned general formula (II) include a compound represented by the general formula (II'): [wherein, R 1' represents hydrogen atom or hydroxyl group; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 ; R 7' represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8' (wherein R 8' represents hydrogen atom, acyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms or amino acid residue) or OR 9' (wherein R 9' represents alkyl group having 1 to 4 carbon atoms or carbohydrate residue); n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms], and preferable examples of jasmonic acids represented by the above-mentioned general formula (III) include a compound represented by the general formula (III'), [wherein, R 1' represents hydrogen atom or hydroxyl group; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 ; R 7' represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8' (wherein R 8' represents hydrogen atom, acyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms or amino acid residue) or OR 9' (wherein R 9' represents alkyl group having 1 to 4 carbon atoms or carbohydrate residue); n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. In the above-mentioned general formulae (I), (II) and (III), examples of alkyl group having 1 to 6 carbon atoms represented by R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , R 6 , R 6a , R 7 , R 8 or R 9 include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, and n-hexyl groups. In the above-mentioned general formulae (I), (II) and (III), examples of alkoxy group having 1 to 6 carbon atoms represented by R 1a , R 1b , R 1c , R 1d , R 1e or R 1f include, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, t-butoxy, n-pentyloxy and n-hexyloxy groups. When R 7 is OM, examples of an alkali metal atom or an alkaline earth metal atom represented by M include, for example, sodium, potassium and calcium. When R 7 is NHR 8 , the acyl group having 1 to 6 carbon atoms represented by R 8 may have either a straight chain or a branched chain, and their examples include, for example, formyl, acetyl, propionyl, butyryl, valeryl, hexanoyl and acryloyl groups. When R 7 is NHR 8 , examples of an amino acid residue represented by R 8 include isoleucyl, tyrosyl, and tryptophyl groups. When R 7 is OR 9 , an example of a carbohydrate residue represented by R 9 is glucopyranosyl group, and when R 6b is -O- carbohydrate residue in the above-mentioned general formula (I), an example of a carbohydrate residue is glucopyranosyl group. In the compounds represented by the general formulae (I), (II) and (III), a double bond may be formed between the neighboring member carbon atoms in the five-membered ring. Illustrative examples of the compound represented by the general formula (I) include those shown as follows; Illustrative examples of the compound represented by the general formula (II) include those shown as follows; Illustrative examples of the compound represented by the general formula (III) include those shown as follows; (Compound I) R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , R 6 : H A double bond is formed between C 3 and C 4 . R 7 : -OH or -OCH 3 n: 1 to 3 (Compound J) R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , R 6 : H R 7 : -OH n: 1 Illustrative examples of the compound represented by the general formula (III) wherein R 1a , R 1b , R 1c , R 1d , R 1e or R 1f is hydroxyl group, or a double bond is formed between the neighboring member carbon atoms in the five-membered ring, include those shown as below; Preferable examples of a compound represented by the general formula (I), (II) or (III) include the compounds wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 and R 6 are hydrogen atoms, R 7 is hydroxyl group or methoxy group, and a side chain consisting of C 1 -C 2 -C 3 - C 4 - C 5 - C 6 does not contain a double bond, or contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 . Jasmonic acids to be used in the present invention which are represented by the general formula (I), (II) or (III) have various stereoisomers (cis-trans isomers and optical isomers), and each isomer can be used alone or in the form of a mixture. All of the jasmonic acids shown above have the effect of improving the productivity in the taxane-type diterpene production, however, tuberonic acid, methyl tuberonate, cucurbic acid, methyl cucurbate, jasmonic acid and methyl jasmonate, which are the compounds represented by the general formula (I), (II) or (III) wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 and R 6 are hydrogen atoms, R 7 is hydroxyl group or methoxy group, n is 1, and a double bond is formed between C 3 and C 4 , are particularly preferable from the view point of their high effectiveness in improving the productivity. These jasmonic acids are prepared by synthesis or extraction and the like from a plant (H.Yamane et al. Agric. Biol. Chem., 44 , 2857-2864(1980)). By the way, there is a description teaching that jasmonic acids are produced by various plants by themselves as a phytohormone-like substance which induces various reactions related to growth promotion, maturation of tissue and appearance of resistance to disease (Teruhiko Yoshihara. Shokubutsu Saib o K o gaku ,Vol 2, No.4 523-531 (1990)). Accordingly, the jasmonic acids involved in the present invention, can be not only added from outside of the culture system, but also produced by the cultured cells or cultured tissues by themselves. An example of a method to promote the production of such endogenous jasmonic acids by the cultured cells or cultured tissues includes addition of microorganism cultures, an extract or a heat-treated substance thereof, or a plant extract to a culture medium, and an illustrative example of such a method is a process of adding a fungus cell wall fraction described by M.J. Mueller et al., Proc. Natl. Acad. Sci. U.S.A., 90 (16), 7490-7494 (1993)). It is also possible to increase the amount of the produced endogenous jasmonic acid by partially damaging cultured cells or cultured tissues mechanically, or with ultraviolet rays, or heat, and one illustrative example of such a process is mechanical cytoclasis of a part of cells (R.A. Cleeman et al., Proc. Natl. Acad. Sci. U.S.A., 89 (11), 4938-4941 (1989). Since jasmonic acids are hardly soluble in water, they are usually dissolved in an organic solvent such as ethanol and methanol or dissolved in a surfactant and the like, then added to a culture medium. Jasmonic acids in liberated form can be used as they are, or they are used in the form of a salt by being neutralized with an alkali. Of the jasmonic acids, those compounds represented by the formula (I) or (III) tend to be in stable trans-form rather than unstable cis-form, since epimerization occurs at the alpha-position to the carbonyl group in the five-membered ring by an acid, an alkali or heat. In an equilibrium experiment utilizing natural or synthesized jasmonic acids, the trans-form is present in the ratio of 90 % and the cis-form is present in the ratio of 10 %. Generally, cis-form is considered to have a higher activity, but jasmonic acids to be used in the present invention include all the stereoisomers of the compounds represented by the above-mentioned formula (I) or (III), and the mixture thereof. Jasmonic acids are required to have a concentration in a culture medium of 0.01 - 1000 µM, and it is particularly preferable, according to the first invention of the present application, to control the concentration of the jasmonic acids to be in the range of 0.1 to 500 µM. Induction of some secondary metabolites by addition of jasmonic acids to plant cell cultures is described in DE 4122208 C1, however, there have been no reports on carrying out tissue culture of a taxane-type diterpene producing plant in the presence of jasmonic acids as a medium additive, and it has been beyond all expectations that the amount of the produced taxane-type diterpene, which has totally different biosynthetic pathway or biosynthesis controlling mechanism from those of the secondary metabolites disclosed in the above-mentioned patent, was increased by the method of the present application. There is a description in the International Publication WO No. 93/17121 that jasmone or methyl jasmone, which has a structure analogous to those of jasmonic acids represented by the formula (I), (II) or (III) to be used in the present invention, is effective in induction of taxol production. However, these compounds do not have a group such as carboxyl, which is represented by the formula: -(CH 2 ) n -CO-R 7 in the formula (I), (II) or (III), unlike the jasmonic acids, and the taxol inducinc activity of these compounds was found to be low (see Comparative Example No. 24). According to the present invention, the culture may be carried out in the presence of at least one ion selected from the group consisting of [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . These compounds may be used alone or in combination. The complex ion containing silver preferably has a concentration in the medium of 10 -8 M - 10 -1 M, and it is further preferable to adjust the concentration to be in the range of 10 -7 M to 10 -2 M. In a further embodiment of the invention, the culture may be carried out in the presence of jasmonic acids and at least one selected from the group consisting of [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . So far, there are no cases reported wherein the tissue culture of a plant producing a taxane-type diterpene is carried out in the presence of such complex ions containing silver. It was beyond all expectations that the amount of the taxane-type diterpene to be produced is increased by the culture carried out in the presence of such complex ions. Examples of the medium to be used for the invention of the present application include those known media which have been conventionally used for the plant tissue culture, such as medium of Murashige & Skoog (1962), medium of Linsmaier Skoog (1965), Woody Plant Medium (1981), Gamborg's B-5 medium and Mitsui's M-9 medium. A phytohormone, and if necessary a carbon source, an inorganic component, vitamins, amino acids and the like may be added as well to these media. As a carbon source, a disaccharide such as sucrose, maltose, and lactose, a monosaccharide such as glucose, fructose and galactose, starch or a mixture of two or more kinds of such sugar sources mixed at an appropriate ratio can be utilized. As an inorganic component, illustrative examples include phosphorus, nitrogen, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, boron, copper, molybdenum, chlorine, sodium, iodine and cobalt, and these components can be added in the form of such a compound as potassium nitrate, sodium nitrate, calcium nitrate, potassium chloride, potassium monohydrogenphosphate, potassium dihydrogenphosphate, calcium chloride, magnesium sulfate, sodium sulfate, ferrous sulfate, ferric sulfate, manganese sulfate, zinc sulfate, boric acid, copper sulfate, sodium molybdate, molybdenum trioxide, potassium iodide, cobalt chloride and the like. As the phytohormone, for example, auxin such as indoleacetic acid (IAA), naphthalenacetic acid (NAA), and 2,4-dichlorophenoxy acetic acid (2,4-D), and cytokinin such as kinetin, zeatin, and dihydrozeatin can be used. As the vitamins, for example, biotin, thiamin (vitamin B1), pyridoxine (vitamin B6), pantothenic acid, inositol, nicotinic acid and the like can be used. As the amino acids, for example, glycine, phenylalanine, leucine, glutamine, cysteine and the like can be added. Generally, the carbon source in a concentration of about 1 - about 30 g/l, the inorganic component in a concentration of about 0.1 µM - about 100 mM, the phytohormones in a concentration of about 0.01 - about 10 µM, and the vitamins and the amino acids respectively in a concentration of about 0.1 - about 100 mg/l are used. According to the present invention, both a liquid medium and such a solid medium that contains agar and gelan gum normally in an amount of 0.1 - 1 % can be used, however, usually a liquid medium is preferable. According to the tissue culture of the present invention, a piece of a tissue or a cell of a root, a growing point, a leaf, a stem, a seed, a pollen, an anther and a calyx and the like of the said plant or cultured cells which are obtained by the tissue culture thereof in the above-mentioned medium or another conventional medium can be used. The present invention can also be applied to neoplastic cell and/or hairy-root, obtained by infecting a plant tissue with Agrobacterium tumefaciens or Agrobacterium rhizogenes . By culturing these tissues or cells in the presence of at least one substance selected from the group consisting of jasmonic acids, compounds containing a heavy metal, complex ions containing a heavy metal, heavy metal ions, amines, and antiethylene agents, cultured tissues or cultured cells having higher taxane-type diterpene productivity than that of those obtained by the tissue culture carried out under the normal culture conditions, can be obtained. When at least one compound selected from compounds containing a heavy metal, complex ions containing a heavy metal, heavy metal ions, amines, and antiethylene agents is used together with jasmonic acids represented by the above-mentioned general formulae (I), (II) or (III), the effect of the first invention of the present application can be enhanced. Taxane-type diterpene can be fractionated from the cultures such as cultured tissues, cultured cells and culture medium, which are obtained according to the above-mentioned process, by extraction with an organic solvent such as methanol. It is also possible to recover the taxane-type diterpene continuously during culture by allowing an appropriate adsorbing agent or an organic solvent coexist in the culture medium. One preferable example of the tissue culture according to the present invention can be illustrated as follows. A piece of a plant body of a plant belonging to genus Taxus, such as a root, a growing point, a leaf, a stem, a seed and the like is sterilized and placed on Woody Plant Medium solidified with gelan gum, and kept at 10 - 35 °C for about 14 - 60 days so that a part of the tissue piece is changed to callus. By subculturing the callus thus obtained, the growing speed is gradually increased and stabilized callus can be obtained. By the stabilized callus, we refer to a callus which remains in callus state during culture without showing differentiation into a shoot or a root and the cells of which have uniform growing speed. Such stabilized callus is transferred to a liquid medium, suited for the growth, such as liquid Woody Plant Medium and grown. The growing speed is further increased in the liquid medium. According to the present invention, the stabilized callus or the cells constituting the above-mentioned callus are grown in a solid medium or a liquid medium in the presence of at least one substance selected from a group consisting of jasmonic acids, [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . And, it is also possible to fractionate the stabilized callus or the cells constituting the said callus into a plurality of layers according to the difference in their specific gravities and grow the cells contained in at least one layer in a culture medium containing at least one substance selected from the group consisting of jasmonic acids, [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . In a generally known method to fractionate the cells according to their specific gravities, density gradient is formed by a medium for centrifugal separation, and the cells are layered over it, then centrifugal separation is carried out. As a medium for centrifugal separation, Ficoll, Percoll (both produced by Pharmacia LKB Biotechnology Co. Ltd.,), sucrose and cesium chloride and the like are used. In the examples including example No.5, the density gradient was produced by the use of Ficoll, however, the medium is not particularly limited to any substance as far as it does not damage the cells. The number of the layers forming the density gradient is not particularly restricted. The difference between the specific gravities of layers is not particularly limited and each difference in the specific gravity can be the same or different. Accordingly, the definition of the density gradient includes a case wherein the gradient changes continuously (the condition wherein the number of the layers forming the density gradient is close to infinite, and the specific gravity difference between each layer is close to 0). The cells can be fractionated into a plurality of layers according to the difference in their specific gravities by thus forming the density gradient, layering the cells and carrying out the centrifugal separation. The specific gravity of the layer to be formed is normally in the range of 1.00 to 1.20 g/ml, preferably in the range of 1.03 to 1.11 g/ml. As a layer to become an object for culture, at least one layer is selected, but it is also possible to select all the layers and culture them. When a plurality of layers are selected and cells contained in the selected layers are cultured, it is possible to culture the cells in these layers individually, but, it is also possible to mix the cells in two or more layers of the selected plurality of layers and culture them. The cultured cells having high taxane-type diterpene productivity can be usually obtained by culturing cells contained in a layer having the specific gravity of 1.07 or less, but it is not always limited to this range, since it may fluctuate depending on the cells to be cultured or the culture conditions. There is also a tendency that the cells in a layer of a higher specific gravity, have a higher content of the taxane-type diterpene at the time when the fractionation is carried out according to the difference in the specific gravities. Accordingly, to ensure that cultured cells which produce the taxane-type diterpene at a high rate can be obtained, it is desirable that the cells in all the fractionated layers are cultured for a certain period, then the concentration of the taxane-type diterpene in the cells of each layer is measured, and the layer containing the cultured cells which produce the taxane-type diterpene at a high rate is selected from among those layers. It is also possible to fractionate the cultured cells into a plurality of layers according to the difference in the specific gravities by preparing a medium for centrifugal separation having one particular specific gravity such as 1.07 g/ml, for example, and carrying out the centrifugal separation according to the above-mentioned method. Furthermore, the invention of the present application can be used together with a method of the present application wherein the culture is carried out by controlling the oxygen concentration in a gas phase in a culture vessel to less than the oxygen concentration in the atmosphere, from the initial stage of the culture, or by controlling the dissolved oxygen concentration in a fluid medium which is in contact with the tissue or the cell to less than the saturated dissolved oxygen concentration at that temperature from the initial stage of the culture. Here, by the initial stage of the culture, we refer to from the time when the culture was started through the 7th day after the start of the culture, and the controlling of the oxygen concentration in the gas phase in the culture vessel or the controlling of the dissolved oxygen concentration in the fluid medium which is in contact with the tissue or the cell is preferably done from the beginning of the culture. The controlling period is not particularly limited, and, the controlling under the said conditions can be done in the entire culture period, or only in a part of the entire culture period, however, it is preferable to carry out the control at least for 3 days during the entire culture period. The oxygen concentration in the gas phase in the culture vessel is required to be controlled to 4 - 15 %, and it is particularly preferable to control it to 6 - 12 %. The dissolved oxygen concentration in the fluid medium is required to be controlled to 1 - 75 % of the saturated dissolved oxygen concentration at that temperature and it is particularly preferable to control it to 10 - 75 %. It is also possible to combine the invention of the present application, with the above method wherein the oxygen concentration is controlled and the method of the present application wherein the cells are fractionated into a plurality of layers according to the difference in their specific gravities, and the cells contained in at least one layer are cultured. Acording to the invention of the present application, it is effective to add jasmonic acids when the cultured cells are in the exponential growth phase or in the stationary phase, and it is particularly preferable to add jasmonic acids in a transitional period from the exponential growth phase to the stationary phase. The same can be said of the timing of the treatment for increasing the amount of the endogenous jasmonic acids to be produced. For example, when cells are subcultured in every 21 days, the 7th -16th day is the suitable time for addition of the jasmonic acids or the treatment to increase the amount of the endogenous jasmonic acids to be produced, and when the cells in the exponential growth phase, for example those on the 7th - 14th day are to be subcultured, the suitable time is immediately after the transplantation. The addition of the jasmonic acids or the treatment to increase the amount of the endogenous jasmonic acid to be produced can be done at one time, in a plurality of parts, or continuously. It is effective to add [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- , after the beginning of the culture and before the transitional period of the cultured cells from the exponential growth phase to the stationary phase, and it is particularly preferable to add them at the beginning of the culture. The addition of the said compounds or the ions can be done at one time, or in a plurality of parts. The temperature for the tissue culture according to the first invention of the present application is usually about 10 - about 35 °C , and preferably about 23 - 28 °C according to the high growing speed. As for the culture period, 14 - 42 days are preferable. When a liquid medium is used for the culture according to the first invention of the present application, the cultured cells can be fractionated from the culture medium after the culture is completed, by such a method as decantation or filtration and the desired taxane-type diterpene can be fractionated from the cultured cells and/or the culture medium by such a method as extraction with an organic solvent. According to the invention of the present application, taxane-type diterpene can be easily obtained in large quantity. When the invention of the present application is to be industrially executed, the efficiency can be further increased by employing the following inventions of the present application in an independent form or in a combined form. That means, it is necessary to supply a gas containing oxygen to a culture liquid to culture tissues or cells of a plant which produces taxane-type diterpene. Normally, air is used for this purpose, however, after an intensive study, the present inventors found that the taxane-type diterpene production can be efficiently carried out by the use of a gas containing 0.03 - 10 %, preferably 0.1 - 5 % of carbon dioxide, as a gas to be introduced to a tank for culturing the tissues or the cells of the plant producing the taxane-type diterpene. The present inventors also found that the productivity of the taxane-type diterpene in the cultures can be remarkably improved and the fluctuation of the taxane-type diterpene productivity due to the subculture can be controlled by carrying cut a two-stage culture of the tissue or the cell of the plant producing the taxane-type diterpene, comprising a first stage using a medium to which an oxidizing agent or a water soluble organic compound containing oxygen is added for obtaining the tissues or the cells which is activated for production of the taxane-type diterpene in the subsequent stage, and a second stage which is carried out such conditions that promote the production of the taxane-type diterpene. Here, examples of the oxidizing agent include peroxodisulfates such as potassium peroxodisulfate and hydrogen peroxide, and examples of the water soluble organic compound containing oxygen include dimethyl formamide, dimethyl sulfoxide, and ethylene glycol and the like. The total concentration of the above-mentioned additive in the culture medium is preferably 10 -6 M - 10 -1 M immediately after the addition, and it is further preferable to control the concentration to be in the range of 10 -5 M to 10 -2 M. The present inventors also found that the high density culture of the tissue or the cell of the plant producing the taxane-type diterpene can be carried out by inoculating the tissues or the cells in a culture medium containing a saccharide in a concentration of 2 - 50 g/l, preferably 10 - 30 g/l, and/or nitrate ion in a concentration of 2 - 50 mmol/l, preferably 10 - 30 mmol/1, then by adding a nutrient source solution containing the saccharide in an amount of 0.2 - 5 g/l, preferably 0.5 - 3 g/l, and/or nitrate ion in an amount of 0.2 - 5 mmol/l, preferably 0.5 - 3 mmol/l per day with respect to the initial volume of the said culture medium, continuously or intermittently to the culture medium, thereby the taxane-type diterpene production volume per culture vessel can be remarkably increased. Here, by the density, we refer to a cell mass per volume of the culture solution in the culture vessel, which is shown in terms of dry cell mass (g) per liter of the culture solution. According to this invention of the present application, it is preferable to carry out culture while the culture medium is renewed by adding the nutrient source solution and simultaneously separating and removing the same volume of the medium from the tissues or the cells and to recover the taxane-type diterpene from at least one selected from the resulting cultures, the medium recovered by removal during the culture, and the medium obtained at the end of the culture. The above invention of the present application is particularly effective in improving the taxane-type diterpene productivity in the high density culture wherein the density of the tissue or the cell of the above-mentioned plant at the start of the culture with respect to the medium volume is 50 g fresh weight/l or higher. Furthermore, though the culture is normally finished when the cells of high density are obtained, the present inventors achieved, through the intensive study, the continuous culture by continuing the culture while the cells are removed, and after further examination, finally completed a continuous culture method. That means, the taxane-type diterpene can be produced with such a high rate that could be hardly attained with the conventional process, by adding the fresh medium continuously or intermittently in such a way that the specific renewing ratio defined by the dimensionless number F = V I /V/µ (wherein, V is the total volume of the culture medium in a culture tank, V I is the feed speed of the fresh medium, and µ is the specific growth rate of the tissues cr the cells) is in the range of 0.1 to 10, and by recovering the taxane-type diterpene from the culture medium containing the tissues or the cells which is continuously or intermittently taken out from the tank and/or the culture solution which does not contain the tissue nor the cell and which is continuously or intermittently taken out from the tank. It is further preferable to set the specific renewing ratio of the culture medium, F, to 0.5 - 5. The saccharide concentration in the culture solution is preferably 5 - 40 g/l, and the nitrate ion concentration in the culture solution is preferably 10 - 40 mmol/l. The present invention can be effective with the cell density in terms of fresh cell weight per litter of 50 - 500 g, however, the higher the density is as far as it is in a range wherein extremely vigorous stirring is not required, the more efficiently the taxane-type diterpene can be produced, thus the preferable density is 200 g or higher per liter. Brief Description of Drawings Fig 1. is a graph showing the change of the yield of the taxol in the culture medium after adding 100 µM of methyl jasmonate. Fig.2 is a graph showing the change of the yield of the baccatin III in the culture medium after adding 100 µM of methyl jasmonate. Best Mode for Carrying Out the Invention The invention will be further illustrated with the following examples and comparative examples, however, these examples are not to be construed to limit the scope of the invention. [Example 1] A part of stem of Taxus baccata LINN which had been previously sterilized with 2 % antiformin solution or 70 % ethanol solution and the like, was placed on solid Woody Plant Medium (containing gelan gum of 0.25 % by weight) to which naphthalenacetic acid had been added to give the concentration of 10 -5 M, and static culture was carried out at 25 °C in a dark place to provide callus of Taxus baccata LINN. One gram (fresh weight) of the callus was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration and shake culture was carried out with a rotary shaker (amplification of 25 mm, 120 rpm) and the callus was subcultured in every 21 days to accelerate the growth rate thereof. One gram (fresh weight) of the cultured cells thus obtained was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration, and shake culture was carried out at 25 °C for 14 days. On the 14th day after starting the culture, methyl ester of tuberonic acid (which is a compound represented by the general formula (I), wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , and R 6a are hydrogen atoms, R 6b is hydroxyl group, R 7 is methoxy group, n is 1 and C 3 and C 4 have a double bond between them) was added as the compound represented by the general formula (I) to give the final concentration of 0.01 - 1000 µM, and the culture was further carried out for another 7 days. After completing the culture, cultured cells of Taxus baccata LINN were harvested by filtration and lyophilized, then the dry weight was measured to obtain the yield of the cultured cells per litre of the liquid medium. Taxane-type diterpenes were extracted from the dried callus with methanol and the like, and they were determined by comparing with standard taxol, cephalomannine, and baccatin III using high performance liquid chromatography to measure the yields of the taxane-type diterpenes. The results are shown in Table 1. [Comparative Example 1] The procedure of Example 1 was carried out except that the methyl ester of tuberonic acid was not added. The results are shown in Table 1. [Example 2] The procedure of Example 1 was carried out except that the methyl ester of tuberonic acid was added successively a total of 4 times in every two days starting from the 7th day after starting the culture (to give the final concentration of 25 µM each time, and to give the total concentration of 100 µM). The results are shown in Table 1. [Example 3] The procedure of Example 1 was carried out except that 100 µM of the methyl ester of tuberonic acid was added on the first day after starting the culture then the culture was further carried out for another 20 days. The results are shown in Table 1. [Example 4] The procedure of Example 1 was carried out except that 100 µM of the methyl ester of tuberonic acid was added on the 7th day after starting the culture and the culture was further carried out for another 14 days. The results are shown in Table 1. concentration of methyl tuberonate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 1 0 14.3 0.4 3.5 1.2 Example 1 0.01 14.3 0.4 4.6 1.3 " 0.1 13.5 0.5 5.5 1.5 " 1 13.2 0.7 6.9 1.8 " 10 13.0 0.9 14.8 2.2 " 100 12.7 12.2 16.5 2.4 " 250 12.5 14.5 21.1 2.2 " 500 11.6 15.0 10.6 2.3 " 1000 7.5 1.2 3.9 1.8 Example 2 100 (25 x 4) 12.9 13.5 22.5 2.3 Example 3 100 7.1 1.0 4.0 1.3 Example 4 100 12.5 10.5 15.6 2.1 [Example 5] The cells with accelerated growth rate obtained by the method of Example 1 were fractionated firstly by a stainless steel mesh and cell clusters having the size of 250 - 840 µm were obtained. A medium having a specific gravity of 1.07 (g/ml) was produced by the use of Ficoll and the above-mentioned cells were layered over it and centrifuged at 700 rpm for 6 minutes. The cells were fractionated into two layers according to the difference of the specific gravity. The cells contained in the layer of 1.07 g/ml or less were fractionated and washed with 2 % sucrose solution three times or more, to wash off Ficoll. After the washing, 1 g (fresh weight) of the cells was transferred to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium and shake culture was carried out at 25 °C for 14 days. On the 14th day after starting the culture, methyl ester of tuberonic acid was added to it to give the final concentration of 250 µM, and the culture was further carried out for another 7 days. After completing the culture, the procedure of Example 1 was carried out. The results are shown in Table 2. The productivity of the taxane-type diterpenes could be greatly improved by the combination of the selection of cells having a particular specific gravity and the addition of the methyl ester of tuberonic acid. [Comparative Example 2] The procedure of Example 5 was carried out except that the methyl ester of tuberonic acid was not added. The results are shown in Table 2. concentration of methyl tuberonate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 2 0 14.2 0.5 5.4 1.5 Example 5 250 12.2 17.4 28.3 3.1 [Example 6] 250 µM of methyl ester of tuberonic acid was added to cultured cells of Taxus brevifolia NUTT obtained on the 14th day after starting the culture by the method of Example 1, and the culture was further carried out for another 7 days. After completing the culture, the procedure of Example 1 was carried out. The results are shown in Table 3. [Comparative Example 3] The procedure of Example 6 was carried out except that methyl ester of tuberonic acid was not added. The results are shown in Table 3. [Example 7] The procedure of Example 6 was carried out except that cultured cells of T. media were used. The results are shown in Table 3. [Comparative Example 4] The procedure of Example 7 was carried out except that the methyl ester of tuberonic acid was not added. The results are shown in Table 3. concentration of methyl tuberonate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 3 0 12.5 0.1 0.2 0.2 Example 6 250 10.0 1.4 3.3 0.5 Comparative Example 4 0 13.6 0.2 0.3 0.1 Example 7 250 9.5 10.4 5.4 0.5 [Example 8] A part of stem of Taxus baccata LINN which had been previously sterilized with 2 % antiformin solution or 70 % ethanol solution and the like, was placed on solid Woody Plant Medium (containing gelan gum of 0.25 % by weight) to which naphthalenacetic acid had been added to give the concentration of 10 -5 M, and static culture was carried out at 25 °C in a dark place to provide callus of Taxus baccata LINN. One gram (fresh weight) of the callus was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration and shake culture was carried out with a rotary shaker (amplification of 25 mm, 120 rpm) and the callus was subcultured in every 21 days to accelerate the growth rate thereof. One gram (fresh weight) of the cultured cells thus obtained was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration, and shake culture was carried out at 25 °C for 14 days. On the 14th day after starting the culture, methyl ester of cucurbic acid (which is a compound represented by the general formula (II) wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , and R 6 are hydrogen atoms, R 7 is methoxy group, n is 1 and C 3 and C 4 have a double bond between them) was added as one of jasmonic acids to give the final concentration of 0.01 - 1000 µM, and the culture was further carried out for another 7 days. After completing the culture, cultured cells of Taxus baccata LINN were harvested by filtration and lyophilized, then the dry weight was measured to obtain the yield of the cultured cells per litre of the liquid medium. Taxane-type diterpenes were extracted from the dried callus with methanol and the like, and they were determined by comparing with standard taxol, cephalomannine, and baccatin III using high performance liquid chromatography to measure the yields of the taxane-type diterpenes. The results are shown in Table 4. [Comparative Example 5] The procedure of Example 8 was carried out, except that the methyl ester of cucurbic acid was not added. The results are shown in Table 4. [Example 9] The procedure of Example 8 was carried out except that the methyl ester of cucurbic acid was added successively a total of 4 times in every two days starting from the 7th day after starting the culture (to give the final concentration of 25 µM each time, and to give the total concentration of 100 µM). The results are shown in Table 4. [Example 10] The procedure of Example 8 was carried out except that 100 µM of the methyl ester of cucurbic acid was added on the first day after starting the culture then the culture was further carried out for another 20 days. The results are shown in Table 4. [Example 11] The procedure of Example 8 was carried out except that 100 µM of the methyl ester of cucurbic acid was added on the 7th day after starting the culture and the culture was further carried out for another 14 days. The results are shown in Table 4. concentration of methyl cucurbate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 5 0 11.3 0.2 3.3 2.4 Example 8 0.01 11.3 0.3 4.3 2.6 " 0.1 11.1 0.3 5.4 3.1 " .1 10.4 0.3 6.7 3.3 " 10 10.4 0.5 11.3 4.0 " 100 9.8 7.2 15.7 4.4 " 250 9.6 10.6 17.7 5.3 " 500 9.3 12.0 13.1 3.0 " 1000 5.7 1.2 4.2 2.8 Example 9 100 (25 x 4) 10.5 14.6 18.2 4.1 Example 10 100 6.1 0.8 3.9 2.8 Example 11 100 9.5 8.4 16.8 4.1 [Example 12] The cells with accelerated growth rates obtained by the method of Example 8 were fractionated firstly by a stainless steel mesh and cell clusters having the size of 250 - 840 µm were obtained. A medium having a specific gravity of 1.07 (g/ml) was produced by the use of Ficoll and the above-mentioned cells were layered over it and centrifuged at 700 rpm for 6 minutes. The cells were fractionated into two layers according to the difference of the specific gravity. The cells contained in the layer of 1.07 g/ml or less were fractionated and washed with 2 % sucrose solution three times or more, to wash off Ficoll. After the washing, 1 g (fresh weight) of the cells was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium and shake culture was carried out at 25 °C for 14 days. On the 14th day after starting the culture, methyl ester of cucurbic acid was added to it to give the final concentration of 250 µM, and culture was further carried out for another 7 days. After completing the culture, the procedure of Example 8 was carried out. The results are shown in Table 5. The productivity of the taxane-type diterpenes could be greatly improved by the combination of the selection of cells having a particular specific gravity and the addition of the methyl ester of cucurbic acid. [Comparative Example 6] The procedure of Example 12 was carried out except that the methyl ester of cucurbic acid was not added. The results are shown in Table 5. concentration of methyl cucurbate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 6 0 11.5 0.3 4.3 2.8 Example 12 250 9.7 22.2 29.7 3.8 [Example 13] 250 µM of methyl ester of cucurbic acid was added to cultured cells of Taxus brevifolia NUTT obtained on the 14th day after starting the culture by the method of Example 8, and the culture was further carried out for another 7 days. After completing the culture, the procedure of Example 8 was carried out. The results are shown in Table 6. [Comparative Example 7] The procedure of Example 13 was carried out except that methyl ester of cucurbic acid was not added. The results are shown in Table 6. [Example 14] The procedure of Example 13 was carried out except that cultured cells of T. media were used. The results are shown in Table 6. [Comparative Example 8] The procedure of Example 14 was carried out except that the methyl ester of cucurbic acid was not added. The results are shown in Table 6. concentration of methyl cucurbate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 7 0 12.5 0.1 0.2 0.2 Example 13 250 11.0 1.2 1.3 0.3 Comparative Example 8 0 13.6 0.2 0.3 0.1 Example 14 250 12.3 5.2 3.9 0.2 [Example 15] A part of stem of Taxus baccata LINN which had been previously sterilized with 2 % antiformin solution or 70 % ethanol solution and the like, was placed on solid Woody Plant Medium (containing gelan gum of 0.25 % by weight) to which naphthalenacetic acid had been added to give the concentration of 10 -5 M, and static culture was carried out at 25 °C in a dark place to provide callus of Taxus baccata LINN. One gram (fresh weight) of the callus was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration and shake culture was carried out with a rotary shaker (amplification of 25 mm, 120 rpm) and the callus was subcultured in every 21 days to accelerate the growth rate thereof. One gram (fresh weight) of the cultured cells thus obtained was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration, and shake culture was carried out at 25 °C for 14 days. On the 14th day after starting the culture, methyl ester of jasmonic acid (which is a compound represented by the general formula (III) wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , and R 6 are hydrogen atoms, R 7 is methoxy group, n is 1 and C 3 and C 4 have a double bond between them, 90 % of which is in the trans-form and 10 % of which is in the cis-form) was added as one of jasmonic acids to give the final concentration of 0.01 - 1000 µM, and the culture was further carried out for another 7 days. After completing the culture, cultured cells of Taxus baccata LINN were harvested by filtration and lyophilized, then the dry weight was measured to obtain the yield of the cultured cells per litre of the liquid medium. Taxane-type diterpenes were extracted from the dried callus with methanol and the like, and they were determined by comparing with standard taxol, cephalomannine, and baccatin III using high performance liquid chromatography to measure the yields of the taxane-type diterpenes. The results are shown in Table 7. [Comparative Example 9] The procedure of Example 15 was carried out except that the methyl ester of jasmonic acid was not added. The results are shown in Table 7. [Example 16] The procedure of Example 15 was carried out except that the methyl ester of jasmonic acid was added successively a total of 4 times in every two days starting from the 7th day after starting the culture (to give the final concentration of 25 µM each time, and to give the total concentration of 100 µM). The results are shown in Table 7. [Example 17] The procedure of Example 15 was carried out except that 100 µM of the methyl ester of jasmonic acid was added on the first day after starting the culture then the culture was further carried out for another 20 days. The results are shown in Table 7. [Example 18] The procedure of Example 15 was carried out except that 100 µM of the methyl ester of jasmonic acid was added on the 7th day after starting the culture and the culture was further carried out for another 14 days. The results are shown in Table 7. [Example 19] The procedure of Example 15 was carried out except that jasmonic acid (which is a compound represented by the general formula (III) wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , and R 6 are hydrogen atoms, R 7 is hydroxy group, n is 1 and C 3 and C 4 have a double bond between them; 90 % of which is in the trans- form and 10 % of which is in the cis-form) was added as one of jasmonic acids to give the final concentration of 0.01 - 1000 µM. The results are shown in Table 8. [Comparative Example 10] The procedure of Example 19 was carried out except that the methyl ester of jasmonic acid was not added. The results are shown in Table 8. [Example 20] The analytical results of taxane-type diterpenes existing in the culture medium of Example 15 prior to the addition of 100 µM of methyl jasmonate, on the third day after the addition, and on the 7th day after the addition, are shown in Fig.1 and Fig.2 On the 7th day of the culture, about half of the taxol and about 70 % of the baccatin III were leaked in the medium. [Comparative Example 11] The procedure of Example 20 was carried out except that the methyl ester of jasmonic acid was not added. The results are shown in Fig.1 and Fig.2. [Example 21] The cells with accelerated growth rate obtained by the method of Example 15 were fractionated firstly by a stainless steel mesh and cell clusters having the size of 250 - 840 µm were obtained. A medium having a specific gravity of 1.07 (g/ml) was produced by the use of Ficoll and the above-mentioned cells were layered over it and centrifuged at 700 rpm for 6 minutes. The cells were fractionated into two layers according to the difference of the specific gravity. The cells contained in the layer of 1.07 g/ml or less were fractionated and washed with 2 % sucrose solution three times or more, to wash off Ficoll. After the washing, 1 g (fresh weight) of the cells was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium and shake culture was carried out at 25 °C for 14 days. On the 14th day after starting the culture, methyl ester of jasmonic acid was added to it to give the final concentration of 250 µM, and the culture was further carried out for another 7 days. After completing the culture, the procedure of Example 15 was carried out. The results are shown in Table 9. The productivity of the taxane-type diterpenes could be greatly improved by the combination of the selection of cells having a particular specific gravity and the addition of the methyl ester of jasmonic acid. [Comparative Example 12] The procedure of Example 21 was carried out except that the methyl ester of jasmonic acid was not added. The results are shown in Table 9. [Example 22] 250 µM of methyl ester of jasmonic acid was added to cultured cells of Taxus brevifolia NUTT obtained on the 14th day after starting the culture by the method of Example 15, and the culture was further carried out for another 7 days. After completing the culture, the procedure of Example 15 was carried out. The results are shown in Table 10. [Comparative Example 13] The procedure of Example 22 was carried out except that methyl ester of jasmonic acid was not added. The results are shown in Table 10. [Example 23] The procedure of Example 22 was carried out except that cultured cells of T. media were used. The results are shown in Table 10. [Comparative Example 14] The procedure of Example 23 was carried out except that the methyl ester of jasmonic acid was not added. The results are shown in Table 10. concentration of methyl jasmonate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 9 0 12.2 0.2 2.8 1.5 Example 15 0.01 12.2 0.3 3.2 1.6 " 0.1 12.1 0.3 4.2 1.6 " 1 11.3 0.4 4.9 1.8 " 10 11.3 0.7 10.8 2.1 " 50 10.9 3.1 10.9 2.2 " 100 9.8 9.2 13.5 2.0 " 250 10.0 12.9 15.1 2.0 " 500 10.6 13.0 12.6 1.9 " 1000 5.9 1.2 3.1 1.8 Example 16 100 (25 x 4) 10.7 14.9 16.7 2.2 Example 17 100 7.2 1.2 4.5 1.7 Example 18 100 9.7 10.6 14.2 2.1 concentration of jasmonic acid (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 10 0 12.2 0.2 1.2 0.4 Example 19 0.01 12.2 0.3 2.2 0.6 " 0.1 12.2 0.3 3.4 0.6 " 1 11.6 0.3 5.9 0.8 " 10 11.5 0.5 8.3 2.6 " 50 11.4 2.5 10.2 2.2 " 100 10.3 7.2 12.8 3.0 " 250 10.1 10.6 14.7 2.7 " 500 10.2 12.0 11.1 1.1 " 1000 6.7 1.2 1.2 0.5 concentration of methyl jasmonate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 12 0 12.6 0.5 6.3 2.2 Example 21 250 10.2 18.7 43.1 3.2 concentration of methyl jasmonate (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 13 0 12.5 0.1 0.2 0.2 Example 22 250 10.2 3.4 4.3 0.5 Comparative Example 14 0 14.2 0.2 0.3 0.1 Example 23 250 12.6 12.4 4.4 0.2 [Example 24] A part of stem of Taxus baccata LINN which had been previously sterilized with 2 % antiformin solution or 70 % ethanol solution and the like, was placed on solid Woody Plant Medium (containing gelan gum of 0.25 % by weight) to which naphthalenacetic acid had been added to give the concentration of 10 -5 M, and static culture was carried out at 25 °C in a dark place to provide callus of Taxus baccata LINN. One gram (fresh weight) of the callus was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration and shake culture was carried out with a rotary shaker (amplification of 25 mm, 100 rpm) and the callus was subcultured in every 21 days to accelerate the growth rate thereof. One gram (fresh weight) of the cultured cells thus obtained was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component was added to give the same concentration, and [Ag(S 2 O 3 ) 2 ] 3- was added to it as a compound containing a heavy metal to give the final concentration of 10 -9 M - 1M. Then shake culture was carried out at 25 °C for 21 days. After completing the culture, cultured cells of Taxus baccata LINN were harvested by filtration and lyophilized, then the dry weight was measured to obtain the growth rate thereof. Taxane-type diterpenes were extracted from the dried callus with methanol and the like, and they were determined by comparing with standard taxol, cephalomannine, and baccatin III using high performance liquid chromatography to measure the yields of the taxane-type diterpenes. The results are shown in Table 11. [[Example 25] The procedure of Example 24 was carried out except that [Ag(S 2 O 3 ) 2 ] 3- was added on the 7th day after starting the culture to give the final concentration of 10 -3 M and the culture was further carried out for another 14 days. After the completion of the culture, the procedure of the Example 24 was carried out. The results are shown in Table 11. [Example 26] The procedure of Example 24 was carried out except that [Ag(S 2 O 3 ) 2 ] 3- was added on the 14th day after starting the culture to give the final concentration of 10 -3 M and the culture was further carried out for another 7 days. After the completion of the culture, the procedure of the Example 24 was carried out. The results are shown in Table 11. [Example 27] The procedure of Example 24 was carried out, except that [Ag(S 2 O 3 ) 2 ] 3- was added on the 18th day after starting the culture to give the final concentration of 10 -3 M and the culture was further carried out for another 3 days. After the completion of the culture, the procedure of Example 24 was carried out. The results are shown in Table 11. [Example 28] The procedure of Example 24 was carried out, except that [Ag(S 2 O 3 ) 2 ] 3- was added successively a total of 5 times at 4 days' intervals starting from the start (0 day) of the culture (to give the final concentration of 2 x 10 -4 M each time, and to give the total concentration of 10 -3 M). The results are shown in Table 11. [Example 29] The procedure of Example 24 was carried out except that methyl ester of jasmonic acid (which is a compound represented by the general formula (III) wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , and R 6 are hydrogen atoms, R 7 is methoxy group, n is 1 and C 3 and C 4 have a double bond between them) was added on the 14th day after starting the culture to give the final concentration of 10 -4 M. The results are shown in Table 11. [Example 30] The procedure of Example 24 was carried out except that the flask was put in a vessel (the capacity of 3000 ml) having a gas feed opening and a gas discharge opening, then the vessel was closed hermetically, and air was so mixed with nitrogen that the concentration of the oxygen in a gas to be supplied to the cells to be cultured became 10 %, and the gas was supplied through the feed opening at the rate of 25 ml per minute. The results are shown in Table 11. [Example 31] The procedure of Example 30 was carried cut except that methyl ester of jasmonic acid was added on the 14th day of the culture to give the final concentration of 10 -4 M. The results are shown in Table 11. [Comparative Example 15] The procedure of Example 24 was carried out except that [Ag(S 2 O 3 ) 2 ] 3- was not added. The results are shown in Table 11. [Comparative Example 16] The procedure of Example 24 was carried out except that silver nitrate Ag(NO 3 ) of 10 -3 M was added at the start (0 day) of the culture instead of [Ag(S 2 O 3 ) 2 ] 3- . The results are shown in Table 11. [Example 32] A part of stem of Taxus baccata LINN which had been previously sterilized with 2 % antiformin solution or 70 % ethanol solution and the like, was placed on solid Woody Plant Medium (containing gelan gum of 0.25 % by weight) to which naphthalenacetic acid had been added to give the concentration of 10 -5 M, and static culture was carried out at 25 °C in a dark place to provide Taxus baccata LINN callus. One gram (fresh weight) of the callus was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component had been added to give the same concentration and shake culture was carried out with a rotary shaker (amplification of 25 mm, 100 rpm) and the callus was subcultured in every 21 days to accelerate the growth rate of the callus. One gram (fresh weight) of the cultured cells thus obtained was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component had been added to give the same concentration, and the flask was placed in a chamber (the capacity of 3000 ml) having a gas feed opening and a gas discharge opening, then the chamber was closed hermetically, and air was so mixed with nitrogen that the concentration of the oxygen in a gas to be supplied to the cells to be cultured became 4 - 15 %, and while the gas was supplied through the feed opening at the rate of 25 ml per minute, shake culture was carried out at 25 °C for 21 days. After completing the culture, cultured cells of Taxus baccata LINN were harvested by filtration and lyophilized, then the dry weight was measured to obtain the growth rate thereof. Taxane-type diterpenes were extracted from the dried cells with methanol and the like, and they were determined by comparing with standard taxol, cephalomannine, and baccatin III using high performance liquid chromatography to measure the yields of the taxane-type diterpenes. The results are shown in Table 12. [Comparative Example 17] The procedure of Example 32 was carried out except that the concentration of the oxygen in a gas to be supplied to the cells to be cultured was controlled to be 20 %. The results are shown in Table 12. [Reference Example 3] The procedure of Example 32 was carried out except that the cultured cells inoculated to the flask were cultured in the atmosphere. The results are shown in Table 12. [Example 33] The procedure of Example 32 was carried out except that the concentration of the oxygen in a gas to be supplied to the cells to be cultured was controlled to be 10 % and the mixed gas was supplied from the start of the culture for 3 days, then air was supplied till the end of the culture (for 18 days). The results are shown in Table 12. [Example 34] The procedure of Example 32 was carried out except that the concentration of the oxygen in a gas to be supplied to the cells to be cultured was controlled to be 10 % and the mixed gas was supplied from the start of the culture for 7 days, then air was supplied till the end of the culture (for 14 days). The results are shown in Table 12. [Example 35] The procedure of Example 32 was carried out except that the concentration of the oxygen in a gas to be supplied to the cells to be cultured was controlled to be 10 %, and the mixed gas was supplied from the start of the culture for 14 days, then air was supplied till the end of the culture (for 7 days). The results are shown in Table 12. [Example 36] The procedure of Example 32 was carried out except that methyl ester of jasmonic acid (which is a compound represented by the general formula (III) wherein R 1a , R 1b , R 1c , R 1d , R 1e , R 1f , R 2 , R 3 , R 4 , R 5 , and R 6 are hydrogen atoms, R 7 is methoxy group, n is 1 and C 3 and C 4 have a double bond between them; 90 % of which is in the trans-form, and 10 % of which is in the cis-form) was added as one of jasmonic acids on the 14th day after starting the culture to give the final concentration of 10 - 1000 µM. The results are shown in Table 20. The productivity of taxane-type diterpene could be remarkably improved by combination of supply of oxygen of low concentration and addition of the methyl ester of jasmonic acid. max oxygen concentration in the gas phase (%) growth rate (times) yield of baccatin III (mg/l) yield of cephalomannine (mg/l) yield of taxol (mg/l) total yield of taxane (mg/l) Comparative Example 17 20 3.01 0.78 1.71 1.46 3.95 Example 32 4 2.09 1.65 5.24 1.78 8.67 " 7 2.60 3.37 7.25 2.49 13.11 " 10 2.90 3.19 7.51 2.96 13.66 " 15 2.82 3.18 6.86 2.18 12.22 Example 33 10 2.79 1.33 4.88 1.74 7.95 Example 34 10 2.62 3.21 7.16 1.75 12.12 Example 35 10 2.66 3.17 7.16 1.92 12.25 Reference Example 3 20 3.03 0.77 1.23 0.95 2.95 max oxygen concentration in gas phase (%) concentration of methyl jasmonate (µM) growth rate (times) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) total yield of taxane (mg/l) Comparative Example 17 20 0 3.01 0.78 1.71 1.46 3.95 Example 32 10 0 2.90 3.19 7.51 2.96 13.66 Example 36 10 10 2.82 2.26 10.24 1.73 14.73 " 10 100 2.45 11.32 22.44 2.29 36.05 " 10 1000 1.47 2.10 5.04 1.47 8.61 [Example 37] A part of stem of Taxus baccata LINN which had been previously sterilized with 2 % antiformin solution or 70 % ethanol solution and the like, was placed on solid Woody Plant Medium (containing gelan gum of 0.25 % by weight) to which naphthalenacetic acid had been added to give the concentration of 10 -5 M, and static culture was carried out at 25 °C in a dark place to provide Taxus baccata LINN callus. One gram (fresh weight) of the callus was inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which the above-mentioned component had been added to give the same concentration and shake culture was carried out with a rotary shaker (amplification of 25 mm, 100 rpm), and the callus was subcultured in every 21 days to accelerate the growth rate thereof. One gram (fresh weight) of the cultured cells thus obtained was fractionated firstly by a stainless steel mesh and cell clusters having the size of 250 - 840 µm were obtained. A density gradient with specific gravities of 1.03, 1.05, 1.07, 1.09 and 1.11 (g/ml) was produced by the use of Ficoll and the above-mentioned cells were layered over it and centrifuged at 700 rpm for 6 minutes. The cells were fractionated into each layer according to the difference of the specific gravity. The cells contained in each layer were so fractionated that they were not mixed each other and washed with 2 % sucrose solution three times or more, to wash off Ficoll. After the washing, about 0.1 g (fresh weight) of the cells were transferred to a culture well having an inner diameter of 18 mm, containing 0.8 ml of liquid Woody Plant Medium and shake culture was carried out at 25 °C for 21 days. After culturing them for 21 days, the whole amount of the cells was transferred to a culture well having an inner diameter of 36 mm containing 3 ml of the above-mentioned liquid medium and shake culture was further continued at 25 °C for another 28 days. After completing the culture, cultured cells of Taxus baccata LINN were harvested by filtration and lyophilized, then the dry weight was measured to obtain the growth weight thereof per litre the liquid medium. Taxane-type diterpenes were extracted from the dried callus with methanol and the like, and they were determined by comparing with standard taxol, cephalomannine, and baccatin III using high performance liquid chromatography to measure the yields of the taxane-type diterpenes. The results are shown in Table 14. [Comparative Example 18] The procedure of Example 37 was carried out except that fractionation according to the density gradient was not carried out after separation of the cell clusters by the stainless mesh. The results are shown in Table 14. [Example 38] The procedure of Example 37 was carried out except that the cultured cells which have the same parent plant, but were induced to callus in different stage were used. Provided that the cells contained in a layer having the specific gravity of 1.07 or more were collected in one group and cultured. The results are shown in Table 14. [Comparative Example 19] The procedure of Example 38 was carried out except that fractionation according to the density gradient was not carried out after separation of the cell clusters by the stainless mesh. The results are shown in Table 14. specific gravity range cell yield (g/l) content of baccatin III (ppm) content of taxol (ppm) content of cephalomannine (ppm) Comparative Example 18 - 12.6 1.5 13.0 27.5 Example 37 <1.03 12.5 7.9 184.0 170.3 1.03-1.05 12.5 32.1 90.8 123.7 1.05-1.07 12.2 16.3 93.5 114.1 1.07-1.09 12.6 0.0 3.9 12.3 1.09-1.11 11.9 0.0 2.1 8.6 1.11< 13.5 0.0 2.5 6.3 Comparative Example 19 - 9.3 256.5 864.0 662.5 Example 38 1.03-1.05 9.0 151.3 1660.5 1050.2 1.05-1.07 9.9 155.7 140.8 804.0 1.07< 9.5 19.0 333.1 161.3 [Example 39] One gram (fresh weight) of the same cultured cells that were used in Example 1 was inoculated to an Erlenmeyer flask containing 20 ml of a liquid containing 10 -5 M - 10 -2 M of potassium peroxodisulfate and shaken at 25 °C for 21 days to carry out the first stage of the culture. After completing the culture, the cultured cells were harvested by filtration and a part of the cells were used as seed cells for the second stage of the culture and the rest of the cells were subjected to the measurement of the cell yield and the taxane content in the cells. Accordingly, 1 g (fresh weight) of the cultured cells were inoculated to an Erlenmeyer flask containing 20 ml of liquid Woody Plant Medium to which naphthalenacetic acid had been added to give the concentration of 10 -5 M and shake culture was carried out at 25 °C for 14 days. On the 14th day of the culture, methyl jasmonate was added to the medium to give the concentration in the medium of 100 µM and the culture was further continued for another 7 days. On the other hand, the rest of the cells obtained in the first stage of the culture were lyophilized, then the dry weight was measured to obtain the cell yield thereof per litre of the liquid medium. The content of taxol in the dried cells was measured by high performance liquid chromatography. The yield of the cells and the yield of taxol were measured for the cells obtained by second stage of the culture in the same manner as that for the cells obtained in the first stage of the culture. The results are shown in Table 15. [Comparative Example 20] The procedure of Example 39 was carried out except that potassium peroxodisulfate was not used. The results are shown in Table 15. additives to be used in the first stage of the cultivation result of the first stage of the culture result of the second stage of the culture concentration of potassium peroxodisulfate in the medium time for addition yield of cells (g/l) content of taxol (ppm) yield of cells (g/l) yield of taxol (mg/l) Example 39 10 -5 M 1st day 17.1 97 15.6 14.0 " 10 -4 M 1st day 16.2 250 15.0 20.4 " 5 x 10 -4 M 1st day 15.5 183 14.4 16.3 " 10 -3 M 1st day 15.2 84 13.0 13.6 " 5 x 10 -3 M 1st day 14.0 45 12.1 11.7 Comparative Example 20 - - 16.5 53 15.4 10.1 [Example 40] A hundred grams (fresh weight) of the same cultured cells that were used in Example 1 were inoculated in a tank for stirred tank culture (capacity of 2 liter) filled with 1 liter of standard liquid Woody Plant Medium (sucrose concentration: 20 g/l, nitrate ion concentration: 14.7 mM, α-naphthalenacetic acid: 10 -5 M) to which 2 mM [Ag(S 2 O 3 ) 2 ] 3- had been added, and the culture was started at 25 °C in the dark at the agitation rate of 40 rpm, while air was fed at 0.1 liter per minute, and a medium containing 20 g/l of sucrose and 20 mM of sodium nitrate was supplied continuously in a period starting from the second day till the 14th day of the culture in such a manner that the amount of the sucrose added in one day became 2 g/l and the amount of nitrate ion added in one day became 2 mmol/l, and the culture solution was continuously taken out through a discharge opening, which was different from the nutrition source feed opening, and to which a stainless filter of 100 mesh was attached, at the same rate as that of the addition of the nutrition source solution (the medium renewing ratio in the culture vessel was 10 % per day) to carry out stirred tank culture for 21 days. After completing the culture, the cultured cells and the medium were collected and the yield of taxol was measured in the same manner as that used in the said Example 1. The results are shown in Table 16. [Comparative Example 21] The procedure of Example 40 was carried out except that the nutrition source was not added midway. The results are shown in Table 25. yield of cells (g dried weight /l) yield of taxol (mg/l) from cells from medium total Example 78 38 31 89 125 Comparative Example 21 22 33 27 60 [Example 41] Fifty grams (fresh weight) of the same cultured cells that were used in Example 1, and 1 liter of liquid Woody Plant Medium were transferred to a culture tank (capacity of 2 liter) and the culture was carried out at 25 °C in the dark at the agitation rate of 40 rpm, at the aeration speed of 0. 1 liter per minute for 14 days. The precipitated cell volume (PCV) measured on the 14th day after starting the culture was 0.2 liter. From the 14th day, supply of a fresh medium, wherein 3mM [Ag(S 2 O 3 ) 2 ] 3- had been added to the medium of the same composition as that of the initial medium, as well as taking out of a culture solution which was free from cells were started. The amount of the fresh medium to be supplied per day was 2/5 of the PCV at that time and the amount of the culture solution free from the cells to be taken out was controlled to be 1 liter. On the 35th day after starting the culture, PCV reached 0.6 liter. After that, the stationary state was maintained by taking out the culture solution containing cells once a day to keep the average PCV to 0.6 liter and by taking out the culture solution free from cells to keep the amount of the culture solution to 1 liter. The culture was carried out for 90 days after the start of the culture. The amount of the fresh medium supplied during the stationary state of 60 days was 15 liters, the amount of the medium taken out of the culture tank was 14 liters and the amount of the cells obtained was 0.15 kg (dry weight) and the specific growth rate µ was 0.08 (day -1 ), the average medium renewing ratio was 2.88. The results of the analysis of cells and medium taken out from the culture tank under stationary state showed that 525 mg of taxol was produced. That was equal to the productivity of 8.8 mg/liter/day. The amount of the taxol contained in the cells and the medium were measured in the same manner as that used in Example 1. [Example 42] Fifty grams (fresh weight) of the same cultured cells that were used in Example 1 and 1 liter of liquid Woody Plant Medium were transferred to a culture tank (capacity of 2 liters) and the culture was carried out in the dark, at the agitation rate of 40 rpm, at 25 °C for 14 days, while an air to which 2 % carbon dioxide gas had been added was fed at 0.1 liter per minute. After completing the culture, the cells and the medium were collected and 15.2 g of dry cells were obtained. Determination of the amount of taxol contained in the cells and in the medium which was carried out in the same manner as that used in Example 1 showed that 31 mg of taxol was produced. [Comparative Example 22] The procedure of Example 1 was carried out except that jasmone was added instead of methyl tuberonate to give the final concentration of 0.1 - 1000 µM. The results are shown in Table 17. [Comparative Example 23] The procedure of Comparative Example 22 was carried out except that jasmone was not added. The results are shown in Table 17. concentration of jasmone (µM) cell yield (g/l) yield of baccatin III (mg/l) yield of taxol (mg/l) yield of cephalomannine (mg/l) Comparative Example 22 0.1 12.2 0.3 3.0 1.2 " 1 12.1 0.4 3.2 1.0 " 10 11.3 0.3 3.3 0.8 " 100 11.3 0.3 3.2 0.6 " 1000 10.9 0.2 2.5 0.8 Comparative Example 23 0 12.2 0.2 2.8 1.5 Industrial Applicability The present invention allows industrial production of a taxane-type diterpene including taxol which is useful as a therapeutic agent for ovarian cancer, mammary cancer, lung cancer and the like.

Claims: A method of producing a taxane-type diterpene wherein tissues or cells of a plant which produce taxane-type diterpenes are cultured in the presence of at least one substance selected from the group consisting of jasmonic acids, [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- , then the taxane-type diterpenes are recovered from the resulting cultures. The method according to claim 1, wherein the culture is carried out in the presence of jasmonic acids. The method according to claim 2, wherein jasmonic acids are compounds represented by the general formula (I): [wherein, R 1a , R 1b , R 1c , R 1d , R 1e and R 1f respectively represent hydrogen atom, hydroxyl group, alkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms; R 2 , R 3 , R 4 , R 5 and R 6a respectively represent hydrogen atom or alkyl group having 1 to 6 carbon atoms; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain one or more double bonds; R 6b represents hydroxyl group or -O- carbohydrate residue; R 7 represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8 (wherein R 8 represents hydrogen atom, acyl group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms or amino acid residue), OR 9 (wherein R 9 is alkyl group having 1 to 6 carbon atoms or carbohydrate residue), or alkyl group having 1 to 6 carbon atoms; n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. The method according to claim 3, wherein jasmonic acids represented by the general formula (I) are compounds represented by the general formula (I'): [wherein, R 1' represents hydrogen atom or hydroxyl group; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 ; R 6b represents hydroxyl group or -O- carbohydrate residue; R 7' represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8' (wherein R 8' represents hydrogen atom, acyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms or amino acid residue) or OR 9' (wherein R 9' represents alkyl group having 1 to 4 carbon atoms or carbohydrate residue); n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. The method according to claim 3, wherein a compound represented by the general formula (I) is tuberonic acid or methyl tuberonate. The method according to claim 2, wherein jasmonic acids are compounds represented by the general formula (II): [wherein, R 1a , R 1b , R 1c , R 1d , R 1e and R 1f respectively represent hydrogen atom, hydroxyl group, alkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms; R 2 , R 3 , R 4 , R 5 and R 6 respectively represent hydrogen atom or alkyl group having 1 to 6 carbon atoms; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain one or more double bonds; R 7 represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8 (wherein R 8 represents hydrogen atom, acyl group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms or amino acid residue), OR 9 (wherein R 9 is alkyl group having 1 to 6 carbon atoms or carbohydrate residue), or alkyl group having 1 to 6 carbon atoms; n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. The method according to claim 6, wherein jasmonic acids represented by the general formula (II) are compounds represented by the general formula (II'): [wherein, R 1' represents hydrogen atom or hydroxyl group; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 ; R 7' represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8' (wherein R 8' represents hydrogen atom, acyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms or amino acid residue) or OR 9' (wherein R 9' represents alkyl group having 1 to 4 carbon atoms or carbohydrate residue); n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. The method according to claim 6, wherein a compound represented by the general formula (II) is cucurbic acid or methyl cucurbate. The method according to claim 2, wherein jasmonic acids are compounds represented by the general formula (III): [wherein, R 1a , R 1b , R 1c , R 1d , R 1e and R 1f respectively represent hydrogen atom, hydroxyl group, alkyl group having 1 to 6 carbon atoms, or alkoxy group having 1 to 6 carbon atoms; R 2 , R 3 , R 4 , R 5 and R 6 respectively represent hydrogen atom or alkyl group having 1 to 6 carbon atoms; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain one or more double bonds; R 7 represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8 (wherein R 8 represents hydrogen atom, acyl group having 1 to 6 carbon atoms, alkyl group having 1 to 6 carbon atoms or amino acid residue), OR 9 (wherein R 9 is alkyl group having 1 to 6 carbon atoms or carbohydrate residue), or alkyl group having 1 to 6 carbon atoms; n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. The method according to claim 9, wherein jasmonic acids represented by the general formula (III) are compounds represented by the general formula (III'), [wherein, R 1' represents hydrogen atom or hydroxyl group; a side chain consisting of C 1 - C 2 - C 3 - C 4 - C 5 - C 6 may contain a double bond between C 1 and C 2 , between C 2 and C 3 , or between C 3 and C 4 ; R 7' represents hydroxyl group, OM (wherein M is alkali metal atom, alkaline earth metal atom or NH 4 ), NHR 8' (wherein R 8' represents hydrogen atom, acyl group having 1 to 4 carbon atoms, alkyl group having 1 to 4 carbon atoms or amino acid residue) or OR 9' (wherein R 9' represents alkyl group having 1 to 4 carbon atoms or carbohydrate residue); n is an integer of 1-7; and in the above-mentioned five-membered ring, a double bond may be formed between the neighboring member carbon atoms]. The method according to claim 9, wherein a compound represented by the general formula (III) is jasmonic acid or methyl jasmonate. The method according to claim 2, wherein the concentration of jasmonic acids in a tissue culture medium is 0.01 - 1000 µM. The method according to claim 2, wherein jasmonic acids are added when the cultured cells are in the exponential growth phase or in the stationary phase. The method according to claim 2, wherein jasmonic acids are added to the culture medium in a plurality of parts or continuously. The method according to claim 1, wherein the culture is carried out in the presence of at least one ion selected from the group consisting of [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . The method according to claim 15, wherein the concentration of complex ions containing silver is 10 -8 M - 10 -1 M. The method according to claim 15, wherein the concentration of complex ions containing silver is 10 -7 M - 10 -2 M. The method according to claim 15, wherein culture is carried out in the presence of jasmonic acids and at least one selected from the group consisting of [Ag(S 2 O 3 ) 2 ] 3- and [Ag(S 2 O 3 ) 3 ] 5- . The method according to claim 1, wherein the taxane-type diterpene is at least one compound selected from the group consisting of taxol, 7-epitaxol, baccatin III, 7-epibaccatin III, cephalomannine, 7-epicephalomannine, 10-deacetylbaccatin III, 10-deacetylcephalomannine, 10-deacetyltaxol, taxagifine, xylosyl cephalomannine, and xylosyl taxol. The method according to claim 1, wherein the plant which produces the taxane-type diterpene is a plant belonging to genus Taxus. The method according to claim 20, wherein the plant belonging to genus Taxus is at least one plant selected from the group consisting of Taxus baccata LINN, Taxus cuspidata SIEB. et ZUCC, Taxus cuspidata SIEB. et ZUCC var. nana REHDER, Taxus brevifolia NUTT, Taxus canadensis MARSH, Taxus chinensis, and Taxus media. The method according to claim 1, wherein cells of the plant which produces the taxane-type diterpene are fractionated into a plurality of layers according to the difference in their specific gravities, and cells contained in at least one layer are cultured. The method according to claim 1, wherein the tissues or the cells of the plant which produce the taxane-type diterpene are cultured by controlling the oxygen concentration in a gas phase in a culture vessel to less than the oxygen concentration in the atmosphere, from the initial stage of the culture, or by controlling the dissolved oxygen concentration in a fluid medium which is in contact with the tissues or the cells to less than the saturated dissolved oxygen concentration at that temperature, from the initial stage of the culture. A method of producing a taxane-type diterpene wherein tissues or cells of a plant which produce a taxane-type diterpene are cultured by carrying out a two-stage culture, comprising a first stage using a medium to which an oxidizing agent or a water soluble organic compound containing oxygen is added and a second stage which is carried out according to the production method of claim 1, then the taxane-type diterpene is recovered from the resulting cultures. The method according to claim 1, wherein the tissues or the cells of the plant which produce the taxane-type diterpene are cultured by inoculating the tissues or the cells in a culture medium containing a saccharide in a concentration of 2 - 50 g/l, and/or nitrate ion in a concentration of 2 - 50 mmol/l, then by adding a nutrient source solution containing the saccharide in an amount of 0.2 - 5 g/l, and/or nitrate ion in an amount of 0.2 - 5 mmol/l per day based on the initial volume of the said culture medium, continuously or intermittently to the culture medium, then the taxane-type diterpene is recovered from the resulting cultures. The method according to claim 25, wherein the culture is carried out while the culture medium is renewed by adding the nutrient source solution and separating and removing the same volume of the culture medium from the tissues or the cells, and the taxane-type diterpene is recovered from at least one substance selected from the resulting tissues and/or cells, the culture medium recovered during the culture and obtained at the end of the culture. The method according to claim 1, wherein a fresh medium is added continuously or intermittently in such a way that the specific renewing ratio defined by the dimensionless number F = V I /V/µ (wherein, V is the total volume of the culture solution in a culture tank, V I is the feed speed of the fresh medium, and µ is the specific growth rate of the tissues or the cells) is in the range of 0.1 to 10, and the taxane-type diterpene is recovered from the culture medium and the tissues or the cells contained in the culture medium which is continuously or intermittently taken out from the tank and/or from the culture medium containing no tissue and cell which is continuously or intermittently taken out from the tank. The method according to claim 1, wherein the tissues or the cells of the plant which produce the taxane-type diterpene are cultured by the use of oxygenic gas containing 0.03 - 10 of carbon dioxide to be introduced to the culture vessel.

Inventors: HARA YASUHIRO, HIGASHI YOSUKE, MATSUBARA KOUICHI, OHNISHI NAOTO, SUGA CHUZO, TABATA HOMARE, YUKIMUNE YUKIHITO, HARA, YASUHIRO, HIGASHI, YOSUKE, MATSUBARA, KOUICHI, OHNISHI, NAOTO, SUGA, CHUZO, TABATA, HOMARE, YUKIMUNE, YUKIHITO, HARA, YASUHIRO MITSUI PETROCHEMICAL INDUSTRIES LTD, MATSUBARA, KOUICHI MITSUI PETROCHEMICAL IND. LTD., OHNISHI, NAOTO MITSUI PETROCHEMICAL INDUSTRIES LTD, SUGA, CHUZO MITSUI PETROCHEMICAL INDUSTRIES, LTD., TABATA, HOMARE MITSUI PETROCHEMICAL INDUSTRIES LTD
Applicants: MITSUI CHEMICALS INC, MITSUI CHEMICALS, INC.
Application year: 1994
Main classification: C12P17
IPC codes: C12N5, C12P17